That jbl amp will work just fine. FYI, you could go a hair higher on wattage, 70-80 wouldn't be a problem. You might miss a decibal or two at full volume. (That shouldn't matter).
THERE'S NO WAY IN HELL, you are playing those subs on your factory alt for the long term. (I read DUAL, and thought oh come on)..
You did see that the subs alone are also on there:
https://www.amazon.com/dp/B07V2NFXZ7/?tag=caraudiocom-20 $169, without the amp, but that amp package will work great for those. You can then buy the amp from skar for $127. They will still ship the amp for free, and you can save yourself $47 buying them separately. (JUST LOOKED BACK, AND MISSED THAT THE PACKAGE COMES WITH WIRING. SO IT'S PROBABLY ABOUT EVEN).
Back to your alt: that amp is rated higher than listed at 906w x 1 RMS @ 1ohm (
https://www.skaraudio.com/products/rp-800-1d-car-amplifier ) and 90% efficient.
906w / .9 = 1006 watts amp draw. Then divide by voltage 14.4v = 69.9 amp draw, (plus your other amp which is about 10amps). You will definitely NEED to do the big 3.
You should have a 105 amp factory alt. You don't
NEED to do it right away, but when you play your stereo, and your headlights dim is usually the easiest sign, then your circuit is too small: the battery (including it's wiring/big 3), your wiring, your connections, something need to be upgraded for the larger draw.
When you play your stereo, and your voltage starts to drop over time, your alternator is not keeping up. It's not able to recharge at a rate equal to or greater than what you are using. I would bet it would take about an hour to two hours at full volume of heavy bass music, with your factory 105 alt to drop your battery below unusable. Unusable meaning, you are not going to want to use your vehicle's electronics like windows, headlights, and eventually when it gets way to the bottom, you won't have any power for fuel injection and your ECU. Long before that it will drop below 12v, and then you might not be able to get it restarted. If it drops that low, you will want to turn the stereo off, and drive a while until it recharges. Doing that is also not good for your factory similar battery. Maybe you can hold out while you search for a deal on an alternator, but when you put that in, it's going to eat at you to play it.
With this setup, until you upgrade the alt, you will be restricted to playing it what I would guess is about 1/2 the time you are driving, (because you will need to let it recharge OR JUST TURN IT DOWN), to keep your battery from dropping to low.
Until you do get an alt, I would keep a real close eye on your battery voltage. If you're not someone that checks your gauges, take a glance at least every minute, and see how long at full volume, with your headlights AND AC on. If you charge a phone or use the cig lighter, or any other plug-ins you might have, get those goin too, really try to find the max limits. If your vehicle has electric engine fans, the: weather, stop and go traffic, and the AC should turn those on (since those are the biggest power draw in a vehicle), and see how long it takes for it to drop to 13v. Then see how long it takes for you to turn it off and go from 13 up to 14ish volts. Then do it again from 14V to 12V and back up to 14v. That should help you plan better to get your voltage back up before you shut it off. I would also turn the stereo off, and let the battery voltage get up to 13v or more before shutting the vehicle off every time. There's some wiggle room, but this should help you know what you need to be aware of, until it's upgraded and make sure you can start back up next time.
